Fixed browser CI tests by downgrading selenium docker image to use older Firefox 64

.gitlab-ci.yml

@@ -343,7 +343,7 @@ browser:build:
       alias: postgresql
     - name: registry.znuny.com/docker/zammad-elasticsearch:latest
       alias: elasticsearch
-    - name: docker.io/elgalu/selenium:latest
+    - name: docker.io/elgalu/selenium:3.141.59-p8
       alias: selenium
     - name: registry.znuny.com/docker/docker-imap-devel:latest
       alias: mail
@@ -354,7 +354,7 @@ browser:build:
       alias: mysql
     - name: registry.znuny.com/docker/zammad-elasticsearch:latest
       alias: elasticsearch
-    - name: docker.io/elgalu/selenium:latest
+    - name: docker.io/elgalu/selenium:3.141.59-p8
       alias: selenium
     - name: registry.znuny.com/docker/docker-imap-devel:latest
       alias: mail
@@ -650,7 +650,7 @@ test:browser:core:chrome_6_postgresql:
   services:
     - name: registry.znuny.com/docker/zammad-postgresql:latest
       alias: postgresql
-    - name: docker.io/elgalu/selenium:latest
+    - name: docker.io/elgalu/selenium:3.141.59-p8
       alias: selenium
 
 .test_browser_integration_template: &test_browser_integration_definition